Tape-shaped molding and belt for ball chain

ABSTRACT

A tape-shaped product and a belt for ball chain are provided. A tape-shaped product of synthetic resin including a tape of a thermoplastic resin, and a preliminarily stretched fibrous member of a thermoplastic resin contained therein along longitudinally parallel edges or in proximity thereto of the tape; and a belt for ball chain, including a tape-shaped product of synthetic resin formed by injection molding together with a fibrous member as an insert of a resin of the same kind as the fibrous member so that the fibrous member is disposed along the longitudinal edges or in proximity thereto, ball-insetting holes disposed at equal intervals, and ball-retaining projections disposed around the holes.

TECHNICAL FIELD

The present invention relates to a tape-shaped product and a belt forball chain used in a guide device for linear motion on a track utilizingthe rolling of a plurality of rolling members, such as balls or rollers(hereinafter representatively referred to as “ball(s)”).

BACKGROUND ART

Hitherto, various tape-shaped products of thermal resins are known, butalmost no proposals have been made regarding a tape-shaped productsuitable for forming a belt including a planar tape portion provide witha multiplicity of holes for retaining another object thereat. As anexample of such a belt including a planar tape portion provided with amultiplicity of holes for holding another object thereat, there is anendless belt retaining balls rollably thereon for a guide device forlinear motion on a track. As disclosed in Japanese Laid-Open PatentApplication (JP-A) 5-52217, such a belt includes ball-retaining portionsintervening a plurality of balls arranged with prescribed intervals in arow, and a flexible connecting member for connection between therespective ball-retaining portions.

For the production of a belt for ball chain (hereinafter sometimesreferred as a ball chain belt), there are known a method of formingprescribed ball-retaining holes in an extruded tape, and a method ofdirect injection molding without via such a tape product. An example ofthe former method is disclosed in JP-A 2001-74048 wherein an elongatedflat tape product (i.e., a belt member) is preliminarily formed byextrusion and is cut in a prescribed length to form a row of holes forloosely retaining balls, and spacer portions are formed between adjacentretaining holes for retaining balls while using the balls as inserts. Inthe case of forming a tape product (a belt member) by extrusion of asynthetic resin and then forming ball-retaining holes for retainingballs rollably, it is difficult to obtain a strength sufficient forusing the product as an endless belt subject to sliding movement.Further, the adhesion between the spacer portions formed by injectionmolding and the belt member is insufficient to cause the dropping-off ofthe spacer portions. For this reason, for the purpose of ensuring atensile strength and a flexural strength of the belt member, JP-A2001-74048 also discloses a method of using two extruders for extrudinga resin functioning as a reinforcing material and a resin coating thereinforcing material to form a tape portion through a common die, and anextrusion forming method of embedding reinforcing members, such as glassfiber, carbon fiber or ceramic fiber along parallel longitudinal edgesof a flat band-shaped belt. However, the above-mentioned method ofco-extruding two types of resins for forming a reinforcing member cannotprovide a sufficient strength, and if a large ratio of stretching isapplied thereto for providing an increased strength, the thermalshrinkability becomes larger, so that the product is not suitable forsuch use as an endless belt for retaining balls rollably in a linearmotion guide device. On the other hand, the fiber, such as glass fiber,carbon fiber or ceramic fiber, of a material different from thebelt-forming material cannot be sufficiently strongly bonded with thebelt-forming material, so that these materials are liable to form a gaptherebetween due to various loads during use, and the strength israpidly lowered if the gap occurs, thus involving a problem regardingthe durability.

Further, in another method of producing a ball chain belt as disclosedin, e.g., JP-A 11-247856, ball frames having a diameter larger than thatof balls used for the ball chain are aligned in projection at prescribedintervals in a metal mold for injection molding of synthetic resin, anda synthetic resin is injected into the metal mold to form a connectingbelt with the ball frames aligned therein, followed by taking-out of theconnecting belt from the metal mold and pushing-in of balls into theball frames of the molded product so as to rollably retain the ballstherein. According to this method, it is very difficult to develop asufficient size accuracy, and even if a sufficient accuracy can beattained, the metal mold production cost becomes very expensive.Further, the taking-out of the product from the mold is difficult, andthe proportion of defectives is liable to be higher due to theoccurrence of fins around the holes.

In another method as disclosed in, e.g., JP-A 5-196037, a plurality ofball pieces disposed between balls and a connecting band connecting theball pieces and provided with ball holes for receiving the balls areintegrally formed by injection molding. In the injection method, resinsinjected out of respective gates are joined together at an intermediatepoint between the gates to form a weld, of which the strength is liableto be lowered.

As described above, there has not been provided a tape-shaped productsuitable for forming a belt including a planar tape portion providedwith a multiplicity of holes for retaining another object thereat.Further, the production of the belt members according to theabove-mentioned methods is complicated, and it is difficult to attain adesired strength by the products.

DISCLOSURE OF INVENTION

The inventors have studied for the purpose of providing a tape-shapedproduct suitable for forming a belt including a planar tape portionprovided with a multiplicity of holes for retaining another objectthereat and having a large tensile strength, and a shaped product havinga large tensile strength as a belt chain belt having a large tensilestrength for rollably retaining balls aligned in a row, to arrive at thepresent invention.

An object of the present invention is to provide a tape-shaped productsuitable for forming a belt including a planar tape portion providedwith a multiplicity of holes or a belt for retaining another object atsuch holes, or a belt for ball chain (i.e., a ball chain belt) having anexcellent ball-retaining power and a durability.

The present invention relates to a tape-shaped product of thermoplasticresin which contains a preliminarily stretched fibrous member ofthermoplastic resin, (hereinafter referred to as “stretched fibrousmember”) along longitudinally parallel edges or in proximity thereto. Itis preferred that the stretched fibrous member comprises a resin havinga good adhesion and moldable together with the resin forming the tapeother than the fibrous member, and that the tape-shaped product has alongitudinal tensile strength of at least 250 MPa and a thermalshrinkability of at most 1%, more preferably a longitudinal tensilestrength of at least 300 MPa and a thermal shrinkability of at most 0.5%The present invention further relates to a tape-shaped product ofsynthetic resin formed by injection molding together with a stretchedfibrous member of a thermoplastic resin having a good adhesion with thestretched fibrous member, and provided with the stretched fibrous membercontained therein at positions along longitudinally parallel edges or inproximity thereto, ball-insetting holes disposed at equal intervals in astraight line, and ball-retaining members (which need not hold the ballsbut are sufficient if they prevent a direct contact of mutually adjacentballs). In the ball chain belt of the present invention, the stretchedfibrous member may comprise a synthetic resin having a good adhesionwith and moldability together with the resin forming the belt other thanthe stretched fibrous member, and the belt may exhibit a tensilestrength of at least 100 MPa, a ball-retaining power of at least 30 MPawhen balls are inset in the ball-insetting holes, and a thermalshrinkability of at most 1%. It is preferred that the tensile strengthis at least 150 MPa, the ball-retaining power is at least 45 MPa whenthe balls are inset in the ball-insetting holes, and the thermalshrinkability is at most 0.5%. In this instance, it is sufficient thatthe stretched fibrous member is disposed at positions outside theinsetting holes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a tape-shaped product of theinvention.

FIG. 2 shows a ball chain belt of the invention, including a planar viewat (a), a longitudinal sectional view at (b) and a lateral side view at(c).

FIG. 3 shows states of stretched fibrous members being set in a mold forforming a tape-shaped product of the invention, including a longitudinalsectional view at (a) and a lateral sectional view at (b).

FIG. 4 is a perspective view of a comparative tape-shaped product notcontaining stretched fibrous members.

FIG. 5 shows a comparative composite tape-shaped product containingco-extruded cores.

FIG. 6 is a view showing a state of forming ball-insetting holes in atape-shaped product of the invention.

FIG. 7 is a view showing a state wherein stretched fibrous members andballs are set in a mold for forming a ball chain belt of the invention.

FIG. 8 shows a comparative ball chain belt free of stretched fibrousmembers, including a planar view at (a), a longitudinal side view at (b)and a lateral side view at (c).

FIG. 9 shows a comparative ball chain belt free of stretched fibrousmembers, including a planar view at (a), a longitudinal side view at (b)and a lateral side view at (c).

FIG. 10 is a view showing a state of forming ball-insetting holes in acomparative tape-shaped product free of stretched fibrous members.

FIG. 11 is a view showing a state wherein rollers are set in a mold forforming a roller-type ball chain belt of the invention.

FIG. 12 shows views of a roller-type ball chain belt of the invention,including a planar view at (a), a longitudinal side view at (b) and alateral side view at (c).

FIG. 13 is a perspective view of a linear motion guide device in which aball chain according to the invention has been incorporated.

FIG. 14 is a perspective view of a linear motion guide device in which aroller-type -ball chain according to the invention has beenincorporated.

FIG. 15 is a sectional view of a ball screw in which a ball chainaccording to the invention has been incorporated.

Respective symbols correspond to respective component members asfollows.

-   -   1: stretched fibrous member, 2: tape member, 3: ball-retaining        hole, 4: ball-retaining member, 5: ball for molding, 6: core, 7:        ball-insetting state, 8: mold, 9: roller-retaining hole, 10:        roller-retaining member, 11: linear motion guide device, 12:        tracking rail, 13: movable block body, 14: ball chain, 15:        linear motion guide device, 16: tracking rail, 17: movable block        body, 18: roller-type ball chain, 19: ball screw, 20: screw        shaft, 21: nut, 22: return pipe, 23: ball chain (ball belt and        balls)

BEST MODE FOR PRACTICING THE INVENTION

A tape-shaped product according to a first invention is shown in FIG. 1,and comprises a stretched fibrous members 1 and injected resin 2. Thestretched fibrous members 1 are set in advance in a mold so as to becontained in the resultant molded product along longitudinally paralleledges or positions proximate thereto of the molded product, and a resinmoldable together with and having a good adhesion with the stretchedfibrous members is molded by injection to form the tape-shaped member(injection-molded resin member) 2 integral with the stretched fibrousmembers 1. As a result, it is possible to obtain a resinous tape-shapedproduct having a longitudinal tensile strength of at least 250 MPa and athermal shrinkability of at most 1%, preferably a longitudinal tensilestrength of at least 300 MPa and a thermal shrinkability of at most0.5%. Incidentally, the thermal shrinkabilities are based on valuesmeasured after allowing samples to stand for 24 hours under no tensionat 40° C. (dry).

A ball chain belt according to a second invention is shown in FIG. 2including a planar view at (a), a longitudinal side view at (b) and alateral side view at (c), and comprises stretched fibrous members 1along longitudinally parallel edges or at positions proximate thereto ofa tape-shaped product, a tape-shaped member (of injection-molded resin)2, a multiplicity of ball-insetting holes 3 disposed at equal intervalsaligned in a central portion of the tape member 2, and ball-retainingmembers 4 each disposed between adjacent ball-insetting holes 3. In thisinstance, it is sufficient that the stretched fibrous members 1 aredisposed at position outside the ball-insetting holes 3. Dashed lines 7in FIG. 2 each represents a state of a ball being inset in position.

A ball chain belt of the present invention as described above may beproduced in the following manner. That is, in a tape-shaped productcontaining stretched fibrous members (FIG. 1) produced in theabove-described manner, holes 3 having a diameter slightly larger thanthat of a ball (or roller) retained therein are formed at equalintervals by perforation as shown in FIG. 6, balls for molding are insetin the holes 3, and ball-retaining members 4 are formed in projection byinjection molding around the holes 3. Alternatively, without via such atape-shaped product, balls 5 having a diameter slightly larger than thatof a ball retained therein and stretched fibrous members 1 are disposedin a mold as shown in FIG. 7, and a prescribed resin is injection-moldedto integrally form the tape member 2 and the retaining members 4. Thus,a shaped product containing the stretched fibrous members along thelongitudinally parallel or at positions proximate thereto and fixing amid portion of the balls is formed, and then the balls for molding aretaken out to provide a ball chain belt. By using the ball chain belt,prescribed balls to be retained are inset at respective holes to providea ball chain rollably retaining the balls.

Herein, the preliminarily stretched fibrous member(s) refers to afibrous member including oriented molecular chains obtained bystretching a yet-unstretched fibrous member formed by fiber spinning.The stretching may be performed by any method capable of providing anenhanced orientation of the fibrous member. For example, it is possibleto adopt a method of subjecting such a yet-unstretched fibrous membercontinuously to a stretching step. Alternatively, such a yet-unstretchedfibrous member may be later subjected to a separate stretching step. Thestretching may be effected in a single step or multiple steps includingtwo or more steps, and may also include a step of heat-treatment, etc.The stretching medium may be gas, liquid or a hot plate and need not berestricted particularly. Further, it is also possible to adopt a directspinning-stretching method wherein a resin ejected out of a spinningnozzle is subjected to drafting. The preliminarily stretched fibrousmember of thermoplastic resin may comprise stretched fiber having atensile strength of at least 300 MPa, preferably 450-1000 MPa and may bein the form of a mono-filament or multi-filaments. The stretched fibrousmember may comprise composite-structured fiber (e.g., core/sheathstructure), combined yarn fiber, twisted yarn fiber or non-circularsection fiber, or any other form as far as it can retain an adhesionwith the injected resin to exhibit a sufficient strength. As thepreliminarily stretched fibrous member of thermoplastic resin, it ispreferred to use a mono-filament (in a sense of including a core-sheathtype composite yarn) of a resin of the same kind as the resin forinjection molding.

The resins moldable together and having a good adhesion with each otherneed not be entirely identical but may be those including principalcomponents of identical resins, may be resins of a same type or family,or may include a stretched fibrous member of which the surface ischemically or physically treated to exhibit such an adhesiveness as notto cause a practically easy separation. The resin for injection moldingis not particularly restricted as far as it allows injection molding,but may comprise various elastomers (e.g., polyester-type, nylon-type,polyolefin-type, acryl-type, fluorine-containing resin-type), or varioussynthetic resins (e.g., polyester-type, nylon-type, polyolefin-type,acryl-type, fluorine-containing resin-type), etc.

Specific combinations of the stretched fibrous member and the injectionmolding resin may include a combination of identical resins, and alsocombinations of a PVDF/PMMA core/sheath composite yarn and acryl-typeelastomer, polyester-type elastomer, PBT-type elastomer, or like; aPVDF/PMMA mixture fiber and the above-mentioned elastomer;PMMA-impregnated UHMWPE fiber string and PMMA, etc.

In the tape-shaped product formed from the stretched fibrous member anda resin moldable together and having a good adhesion therewith throughinjection molding, the stretched fibrous member may desirably occupy aratio of 10-70%, preferably 20-60%, of a sectional area perpendicular tothe longitudinal direction. The ratio can vary depending on the size,desired strength, etc., of the tape-shaped product.

In the tape-shaped product of the present invention, the molded resinportion other than the fibrous member has an orientation which is lowerthan that of the fibrous member and in such a degree as to provide athermal shrinkability of the tape-shaped product of preferably at most1%, more preferably at most 0.5%.

The tape-shaped product of the present invention may have a shape ofsection perpendicular to the longitudinal direction, which shape is notrestricted to a quadrangle or rectangle having 4 sides, but may also bea trigon, a polygon, each capable of including one or more curved sides,or further an ellipse or a shape formed by dividing an ellipse into twohalves.

The tape-shaped product of the present invention may have a section asdescribed above exhibiting a ratio of a maximum thickness to a width ina range of 1:50-1:1, preferably 1:20-1:1, further preferably 1:15-1:2.It is particularly preferred that the tape-shaped product has asectional shape of a rectangle exhibiting a ratio of a maximum thicknessto a width of 1:15-1:2.

A ball chain obtained by insetting balls in a tape-shaped product of thepresent invention may preferably be used as a ball-connecting member ina linear motion guide device equipped with a ball-retaining endlesscirculation path, and in a ball screw device as disclosed in, e.g., JP-A11-37246.

EXAMPLES

Hereinbelow, the present invention will be described more specificallybased on Examples and Comparative Examples. Incidentally, themeasurement conditions for thermal shrinkability, tensile strength andelongation in the following Examples and Comparative Examples are asfollows.

(Measurement Method and Measurement Conditions)

(1) Thermal Shrinkability

Measured at a temperature of 40° C. (dry) for a time of 24 hours.

(2) Tensile Strength and Elongation

Measured by subjecting a test piece of 50 mm in length to a tensilespeed of 50 mm/min. by using Tension UCT=100 Model (made by OrientecK.K.) in an environment at a temperature of 23° C.

(3) Ball-Retaining Strength of Ball Chain Belt.

A ball is inset in a third hole from an end of a ball chain belt, whichis then subjected to measurement in the same manner as tensile strength.

A ball chain belt is provided with circular holes and therefore hasdifferent sectional areas at respective positions, and the breakageoccurs at a portion of the smallest sectional area. The ball-retainingstrength is calculated based on the smallest sectional area.

Physical properties of products obtained in Examples and ComparativeExamples are inclusively shown in Tables 1 and 2.

Example 1

A polyester elastomer of MFR=10 was spun at a resin temperature of 240°C. through a 50 mm-dia. extruder to form an unstreched filament. Theunstretched filament was stretched at 5.8 times in a hot air oven of150° C. and relaxed by 10% in a hot air oven at 180° C. to obtain astretched filament of 200 μm. The stretched filament exhibited a tensilestrength of 470 MPa and an elongation of 86%.

Then, the stretched filament was set in a mold for injection molding asshown in FIG. 3 and an identical resin as the stretched filament wasinjected at 280° C. in the mold to form a tape-shaped product as shownin FIG. 1 having a width of 0.65 mm and a thickness of 0.24 mm. Thestretched filament occupied 40% of a sectional area perpendicular to thelongitudinal direction. As is understood form the physical propertiesshown in Table 1, the shaped product exhibited a high tensile strength,a low thermal shrinkability, and thus a good size accuracy.

Comparative Example 1 Comparative Example 1-(1)

An identical resin as in Example 1 was used in the same manner as inExample 1 except for not setting the stretched filament to form atape-shaped product as shown in FIG. 4 having a width of 0.65 mm and athickness of 0.24 mm. The product exhibited a much lower tensilestrength of 61 MPa than the shaped product of Example 1.

Comparative Example 1-(2)

A polyester elastomer of MFR=10 was spun at a resin temperature of 240°C. through a 50 mm-dia. extruder to form an unstretched filament. Then,similarly as in Example 1, the unstretched filament was set in a moldfor injection molding as shown in FIG. 3, and an identical resin as theunstretched filament was injected into the mold for injection molding,to form a tape-shaped product as shown in FIG. 1 having a width of 0.65mm and a thickness of 0.24 mm. The product exhibited a much lowertensile strength of 65 MPa than the shaped product of Example 1.

From these Comparative Examples, the effectiveness of disposing thestretched filaments in Example 1 is understood.

Comparative Example 2

A tape-shaped product not containing stretched fibrous members unlikethe shaped product of Example 1 was produced by extrusion.

2-(1)

A tape-shaped product as shown in FIG. 4 was obtained by using a 50mm-dia. extruder instead of injection molding in Example 1.

2-(2)

A tape-shaped product was formed by extrusion in the same manner as inthe above 2-(1), followed successively by stretching at 5.8 times in ahot air oven at 150° C. and relaxation by 10% in a in a hot air oven at180° C. to obtain a tape-shaped product as shown in FIG. 4.

2-(3)

A tape-shaped product was formed by extrusion in the same manner as inthe above 2-(1), followed successively by stretching at 6.25 times in ahot air oven at 180° C. and relaxation by 30% in a hot air oven at 320°C. to obtain a tape-shaped product as shown in FIG. 4.

2-(4)

A tape-shaped product as shown in FIG. 4 was obtained in the same manneras in the above 2-(2) except that the stretching ratio was changed to6.9 times.

The tape-shaped products of Comparative Examples 2-(1) to 2-(4) notcontaining stretched filaments but obtained through extrusion exhibitedlower tensile strengths. The extruded products when further subjected tostretching exhibited a large tensile strength but were accompanied withan undesirably larger thermal shrinkability of the shaped products at alarger stretching ratio. Further, in any case, the products failed toexhibit a sufficient strength compared with the shaped product ofExample 1.

Example 2

A core/sheath-type composite yarn (core/sheath ratio=80/20% by volume)with a core of polyester elastomer of MFR=10 and a sheath of polyesterelastomer of MFR=17 was spun at a resin temperature of 240° C. to forman unstretched filament. The unstretched filament was stretched at 5.8times in a hot air oven of 180° C. to form a stretched filament of 200μm. The stretched filament exhibited a tensile strength of 437 MPa andan elongation of 71%. By using the stretched filament and a polyesterelastomer of MFR=10, a tape-shaped product as shown in FIG. 1 having awidth of 0.65 mm and a thickness of 0.24 mm was obtained in the samemanner as in Example 1. In the tape-shaped product, the stretchedfilament occupied 40% of a sectional area perpendicular to thelongitudinal direction. The shaped product also exhibited excellentphysical properties similarly as the shaped product of Example 1.

Comparative Example 3

A tape-shaped product (as shown in FIG. 5) having cores 6 correspondingto the stretched filament in Example 2 was produced by co-extrusion.

3-(1)

Instead of the injection molding in Example 2, a polyester elastomer ofMFR=10 and a polyester elastomer of MFR=17 were co-extended so that thepolyester elastomer of MFR=10 formed 0.2 mm-dia. cores along both edgesof a shaped tape, thus producing a tape-shaped product (width=0.65 mm,thickness=0.24 mm, core diameter=0.2 mm) as shown in FIG. 5 containingcores 6.

3-(2)

A core-containing tape-shaped product was formed by co-extrusion in thesame manner as in the above 3-(1), and then stretched at 5.8 times in ahot air oven at 150° C. and further relaxed by 10% in a hot air oven at180° C. to obtain a core-containing tape-shaped product (width=0.65 mm,thickness=0.24 mm, core diameter=0.2 mm) as shown in FIG. 5

3-(3)

A core-containing tape-shaped product was formed by co-extrusion in thesame manner as in the above 3-(2), and then stretched at 6.25 times in ahot air oven at 180° C. and further relaxed by 10% in a hot air oven at220° C. to obtain a core-containing tape-shaped product (width=0.65 mm,thickness=0.24 mm, core diameter=0.2 mm) as shown in FIG. 5

3-(4)

A core-containing tape-shaped product (width=0.65 mm, thickness=0.24 mm,core diameter=0.2 mm) as shown in FIG. 5 was produced in the same manneras in the 3-(2) above except that the stretch ratio was changed to 6.7times.

From the above 3-(1) to 3-(4), the stretched core-containing tape-shapedproducts obtained by forming a tape-shaped product containingcore-forming resin along both edges thereof by extrusion and subsequentstretching failed to exhibit a sufficient strength compared with thetape-shaped product obtained by injection molding together with thestretched filament and, if the stretching ratio was further increasedfor providing an increased strength, were liable to cause a separationbetween the cores and the tape.

Example 3

A 6/66-copolymer nylon resin having a relative viscosity of 3.5 was spunat a resin temperature of 230° C. through a 50 mm-dia. extruder toobtain an unstretched filament. The unstretched filament was subjectedto a first step-stretching at 3.6 times in a warm water bath at 85° C.and then a second step-stretching at 1.5 times in a hot air oven at 185°C., followed further by relaxation by 15% in a hot air oven at 165° C.to obtain a stretched filament. The stretched filament exhibited atensile strength of 815 MPa and an elongation of 45 %. Then, similarlyas in Example 1, the stretched filament was set in a mold for injectionmolding as shown in FIG. 3, and an identical resin as the stretchedfilament was injected at 240° C. into the mold to form a tape-shapedproduct as shown in FIG. 1. The stretched filament occupied 40% of asectional area perpendicular to the longitudinal direction of theproduct. The shaped product exhibited excellent physical propertiesincluding a large tensile strength of 581 MPa and a small thermalshrinkability of 0.3%.

Example 4

A polyvinylidene fluoride resin of η inh=1.0 (“KF#1000”, made by KurehaChemical Industry Co., Ltd) was spun at a resin temperature of 260° C.through a 50 mm-dia. extruder to obtain an unstretched filament. Theunstretched filament was subjected to a first step-stretching at 5.6times in a glycerin bath at 170° C. and then a second step-stretching at1.15 times in a glycerin bath at 165° C., followed further by relaxationby 10% in a glycerin bath at 160° C. to obtain a stretched filament. Thestretched filament exhibited a tensile strength of 752 MPa and anelongation of 35%. Then, similarly as in Example 1, the stretchedfilament was set in a mold for injection molding as shown in FIG. 3, andan identical resin as the stretched filament was injected at 240° C.into the mold to form a tape-shaped product as shown in FIG. 1. Thestretched filament occupied 40% of a sectional area perpendicular to thelongitudinal direction of the product. The shaped product also exhibitedexcellent physical properties similarly as the shaped product of Example3.

Example 5

The same 6/66 copolymer nylon as used in Example 3 was formed into astretched filament of 200 μm in the same manner as in Example 3 exceptfor changing the second stretching ratio to 1.4 times. The stretchedfilament exhibited a tensile strength of 761 MPa. Then, similarly as inExample 1, the stretched filament was set in a mold for injectionmolding, and an identical resin as in Example 4 was injected at 240° C.into the mold to form a tape-shaped product as shown in FIG. 1. Thestretched-filament occupied 40% of a sectional area perpendicular to thelongitudinal direction of the shaped product. The shaped product alsoexhibited excellent physical properties.

While the products of both Examples 4 and 5 exhibited excellent physicalproperties, the tape-shaped product of Example 4 exhibited betterphysical property in spite of almost equal strengths of the stretchedfilaments in these Examples. This is attributable to a difference inadhesion between the resin of the stretched filament and the injectedresin. Thus, a better adhesion between a stretched filament and aninjected resin results in better development of the property of thestretched filament in the tape-shaped product.

Example 6

A polyester resin (IV=1.0) was spun at a resin temperature of 275° C.through a 50 mm-dia. extruder to obtain an unstretched filament. Theunstretched filament was stretched at 5.5 times and then relaxed by 15%to obtain a stretched filament. Then, similarly as in Example 1, thestretched filament was set in a mold for injection molding as shown inFIG. 3, and an identical resin as in Example 1 was injected at 280° C.into the mold to form a tape-shaped product as shown in FIG. 1. Thestretched filament occupied 40% of a sectional area perpendicular to thelongitudinal direction of the product. The shaped product exhibitedsimilarly excellent physical properties as the product of Example 3.

Comparative Example 4

Stretched filament-containing tape-shaped product was prepared byinjection of a resin different from the stretched filament.

4-(1)

A core-containing unstretched tape was formed by co-extrusion of anidentical polyester resin as used in Example 6 and a polyester elastomerof MFR=1.0. The tape was then subjected to stretching and relaxationheat treatment in a similar manner as in Example 6 to obtain acore-containing stretched tape-shaped product (width=0.65 mm,thickness=0.24 mm, core diameter=0.2 mm). As is understood from thephysical properties shown in Table 1, the tape-shaped product exhibiteda sufficient strength but failed to exhibit a size stability due to alarge thermal shrinkability.

4-(2)

A tape-shaped product was tried to be formed in the same manner as inExample 1 except for using a stretched filament of polyvinylidenefluoride resin obtained in the same manner as in Example 4 and apolyester elastomer of MFR=10 identical to the one used in Example 1,but the stretched filament of polyvinylidene fluoride resin was meltedat-the time of injection molding. TABLE 1 Stretched filament Shapedproduct Strength Tape portion Strength Shink Example Shaping method*Material** [MPa] core Material** [Mpa] [%] 1 SF-inserted injection PEEMFR10 470 PEE MFR10 338 0.3 Comp. 1-(1) injection PEE MFR10 61 0.1 Comp.1-(2) USF-inserted injection PEE MFR10 PEE MFR10 65 0.1 Comp. 2-(1) tapeextrusion PEE MFR10 70 0.1 Comp. 2-(2) tape extrusion-stretching PEEMFR10 235 2.5 Comp. 2-(3) do. PEE MFR10 198 0.3 Comp. 2-(4) do. PEEMFR10 293 3.3 2 SF-inserted injection core: PEE MFR10 437 PEE MFR10 3200.3 sheath: PEE MFR17 Comp. 3-(1) core/tape extrusion yes core: PEEMFR10 71 0.1 sheath: PEE MFR 17 Comp. 3-(2) core/tapeextrusion-stretching yes do. 198 2.3 Comp. 3-(3) do. yes do. 179 0.3Comp. 3-(4) do. yes do. 250 3.1 3 SF-inserted injection 6/66 copolymernylon 815 6/66 copolymer nylon 581 0.3 4 do. PVDF 752 PVDF 522 0.3 5 do.6/66 copolymer nylon 761 PVDF 419 0.3 6 do. polyester 653 PEE MFR10 4550.3 Comp. 4-(1) core/tape extrusion-stretching yes core: polyester 365 3sheath: PEE MFR10 Comp. 4-(2) SF-inserted injection PVDF 752 PEE MFR10PVDF melted*Abbreviation used: SF = stretched filament, USF = unstretched filament**Abbreviation used: PEE = polyester elastomer, MFR = melt flow rate,PVDF = polyvinylided fluoride

Next, examples of production of ball chain belts are described.

Example 7

As shown in FIG. 7, balls were set at equal intervals in a mold, thestretched filament prepared in Example 1 was disposed at such positionsas to be contained along two edges parallel to the longitudinaldirection of the resultant shaped product, and an identical resin(polyester elastomer of MFR=1.0) as the stretched filament was injectedinto the mold to obtain a ball chain belt as shown in FIG. 2 having awidth of 2.24 mm, a thickness of 0.24 mm, a hole diameter of 1.63 mm anda hole-hole pitch of 1.73 mm. The stretched filament occupied a portionof sectional area perpendicular to the longitudinal direction at ratiosof 5% at a ball-retainer portion (spacer portion) and 43% at a holediameter position. As the physical properties thereof are shown in Table2, the ball chain belt exhibited a high tensile strength and also a highstrength at the ball-retaining position, and further a good sizestability due to a small thermal shrinkability. The stretched filamentexhibited a good adhesiveness without peeling.

Comparative Example 5

A ball chain belt (width=2.24 mm, thickness=0.24 mm, hole diameter=1.63mm, hole-hole pitch=1.73 mm) as shown in FIG. 8 (wherein a dashed line 7represents a ball-inset state) was obtained by injection molding in thesame manner as in Example 7 except for omitting the stretched filament.

Example 8

A tape-shaped product having a width of 2.24 mm and a thickness of 0.24mm prepared in a similar manner as in Example 1 was perforated to formholes having a diameter of 1.63 mm at a hole-hole pitch of 1.73 mm.Then, the perforated tape-shaped product was set in a mold, balls formolding were inset in the holes thereof, and insert molding wasperformed by injecting a polyester elastomer of MFR=10 to obtain a ballchain belt as shown in FIG. 2.

Comparative Example 6

Tape shaped products of different stretching ratios were perforated andsubjected to insert molding in similar manners as in Example 8 toproduce ball chain belts.

6-(1)

An identical resin (polyester elastomer of MFR=10) as used in Example 7was extruded through a 50 mm-dia. extruder to form a tape product(width=2.24 mm, thickness=0.24 mm) as shown in FIG. 4, which was thenperforated to form holes having a diameter of 1.63 mm at a hole-holepitch of 1.73 mm as shown in FIG. 6. Then, the perforated tape-shapedproduct was set in a mold, balls for molding were inset in the holes,and insert molding was performed to obtain a ball chain belt as shown inFIG. 8.

6-(2)

An identical resin as used in Example 7 was extruded into a tape-shapedproduct in the same manner as in the above 6-(1), which was thenstretched at 5.8 times in a hot air oven at 150° C. and then relaxed by10% in a hot air oven at 180° C. to obtain a stretched tape. The tapewas used for perforation and insert molding in the same manner as in theabove 6-(1) to obtain a ball chain belt as shown in FIG. 8.

6-(3)

A ball chain belt was obtained in the same manner as in the above 6-(2)except for changing the stretching ratio to 6.9 times.

6-(4)

An identical resin as used in Example 7 was extruded into a tape-shapedproduct in the same manner as in the above 6-(1), which was thenstretched at 6.25 times in a hot air oven at 180° C. and then relaxed by30% in a hot air oven at 220° C. to obtain a stretched tape. The tapewas used for perforation and insert molding in the same manner as in theabove 6-(1) to obtain a ball chain belt as shown in FIG. 8.

In the above 6-(1) to 6-(4), there occurred molding failures, such asinsufficient filling of resin at the spacer portions and “fins” causedby entering of resin into holes.

Example 9

Insert molding was performed in the same manner as in Example 7 exceptfor using the core/sheath composite stretched filament obtained inExample 7 to prepare a ball chain belt as shown in FIG. 2.

Comparative Example 7

Core-containing composite tapes were prepared by co-extruding apolyester elastomer of MFR=10 as a core resin together with a polyesterelastomer of MFR=17, and used for production of ball chain belts asshown in FIG. 9, wherein a dashed line 7 represents a ball-inset state.

7-(1)

A composite tape containing core was prepared by co-extruding apolyester elastomer of MFR=10 as a core resin together with a polyesterelastomer of MFR=17. The tape was subjected to perforation and insertmolding in the same manner as in Example 6 to obtain a ball chain beltas shown in FIG. 9.

7-(2)

A core-containing composite tape was prepared by co-extruding apolyester elastomer of MFR=10 as a core resin together with a polyesterelastomer of MFR=17 and there stretched at 5.8 times in a hot air ovenat 150° C., followed by relaxation by 10% in a hot air oven at 180° C.to obtain a stretched tape. The tape was subjected to perforation andthen insert molding in the same manner as in Comparative Example 6 toobtain a ball chain belt as shown in FIG. 9.

7-(3)

A ball chain belt was obtained in the same manner as in the above 7-(2)except for changing the stretching ratio to 6.7 times.

7-(4)

A core-containing composite tape was prepared by co-extruding apolyester elastomer of MFR=10 as a core resin together with a polyesterelastomer of MFR=17 and then stretched at 6.25 times in a hot air ovenat 180° C., followed by relaxation by 30% in a hot air oven at 220° C.to obtain a stretched tape. The tape was subjected to perforation andthen insert molding in the same manner as in Comparative Example 6 toobtain a ball chain belt as shown in FIG. 9.

In any case of the above 7-(1) to 7-(4), many defective productsoccurred due to difficulty of the molding, and the products obtainedapparently normally were far from practical use due to small tensilestrength and small strength at the retaining portions.

Example 10

The nylon stretched filament prepared in Example 3 was set in a mold asshown in FIG. 7, and an identical resin as the stretched filament wasinjected into the mold to obtain a ball chain belt (width=2.24 mm,thickness=0.24 mm, hole diameter=1.63 mm, hole-hole pitch=1.73 mm) asshown in FIG. 2 in a similar manner as in Example 7.

Example 11

The polyvinylidene fluoride resin stretched filament prepared in Example4 was set in a mold as shown in FIG. 7, and an identical resin as thestretched filament was injected into the mold to obtain a ball chainbelt (width=2.24 mm, thickness=0.24 mm, hole diameter=1.63 mm, hole-holepitch=1.73 mm) as shown in FIG. 2 in a similar manner as in Example 7.

Example 12

The nylon stretched filament prepared in Example 5 was set in a mold asshown in FIG. 7, and an identical resin as the stretched filament wasinjected into the mold to obtain a ball chain belt (width=2.24 mm,thickness=0.24 mm, hole diameter=1.63 mm, hole-hole pitch=1.73 mm) asshown in FIG. 2 in a similar manner as in Example 7. The stretchedfilament occupied a portion of sectional area perpendicular to thelongitudinal direction at ratios of 5% at a ball-retainer portion(spacer portion) and 43% at a hole diameter position.

The products of Examples 11 and 12 both exhibited excellent results. Thereason why the product of Example 11 exhibited better property is thatthe adhesion between the stretched filament and the injected resin wasbetter in Example 11 similarly as in the case of Examples 4 and 5.

Comparative Example 8

The polyvinylidene fluoride resin stretched filament prepared in Example4 was set in a mold as shown in FIG. 7, and a polyester elastomer ofMFR=10 was injected into the mold for insert molding to produce a balchain belt (width=2.24 mm, thickness=0.024 mm, hold diameter=1.63 mm,hole-hole pitch=1.73 mm) as shown in FIG. 2, in a similar manner as inExample 7, whereas the polyvinylidene fluoride resin was melted at thetime of the insert molding.

Example 13

The polyester stretched filament prepared in Example 6 was set in a moldas shown in FIG. 7, and a polyester elastomer of MFR=10 was injectedinto the mold to obtain a ball chain belt (width=2.24 mm, thickness=0.24mm, hole diameter=1.63 mm, hole-hole pitch=1.73 mm) as shown in FIG. 2in a similar manner as in Example 7.

The ball chain belts prepared in the above Examples 7-13 all exhibitedsufficiently large tensile strength and strength at the retainingportion, thus showing excellent performances as a ball chain belt.

Comparative Example 9

Glass fiber (multi-filaments in a form of bundle of 120 filaments ofeach 9.4 μm in diameter) wound about a bobbin was supplied to a die andthe polyester elastomer used in Example 7 was heated through an extruderand supplied to the die to be extruded so as to cover the glass fiber,thereby obtaining a core-containing composite tape-shaped product asshown in FIG. 5. Then, the tape-shaped product was subjected toperforation and insert molding in a similar manner as in ComparativeExample 6 to obtain a ball chain belt as shown in FIG. 9, wherein theadhesion between the glass fiber and the polyester elastomer wasinsufficient to cause peeling of the glass fiber and cutting offilaments.

Comparative Example 10

A ball chain belt as shown in FIG. 9 was prepared in the same manner asin Comparative Example 9 except for using carbon fiber (multifilamentsin a form of bundle of 80 filaments of each 10 μm in diameter). In thebelt, the adhesion between the carbon fiber and the polyester elastomerwas insufficient to cause peeling of the carbon fiber and cutting offilaments. TABLE 2 Ball retainer Stretched filament Injection TensileRetaining Thermal Shaping Strength Extruded molded strength strengthshrink Molding Example method* Material** [MPa] tape material**Perforation material** [MPa] [MPa] [%] defects*** 7 SF-inserted PEEMFR10 470 213 73 0.3 A injection Comp. 5 injection PEE MFR10 61 53 0.3 A8 Method 1 PEE MFR10 470 yes PEE MFR10 207 38 0.3 B Comp. 6-(1) Method 2PEE MFR10 yes PEE MFR10 70 37 0.1 C Comp. 6-(2) Method 3 PEE MFR10 yesPEE MFR10 113 35 3.1 C Comp. 6-(3) Method 3 PEE MFR10 yes PEE MFR10 19535 3.8 C Comp. 6-(4) Method 3 PEE MFR10 yes PEE MFR10 98 37 0.3 C 9SF-inserted core: 437 PEE MFR10 208 110 0.3 A injection PEE MFR10sheath: PEE MFR17 Comp. 7-(1) Method 4 core: PEE MFR10 yes PEE MFR10 6835 0.2 C sheath: PEE MFR17 Comp. 7-(2) Method 5 do. yes PEE MFR10 100 352.8 C Comp. 7-(3) Method 5 do. yes PEE MFR10 165 34 3.3 C Comp. 7-(4)Method 5 do. yes PEE MFR10 89 38 0.3 C 10 SF-inserted 6/66 co-Ny 8156/66 co-Ny 464 140 0.2 A injection 11 SF-inserted PVDF 752 PVDF 383 1310.3 A injection 12 SF-inserted 6/66 co-Ny 761 PVDF 311 86 0.3 Ainjection 13 SF-inserted polyester 653 PEE MFR10 329 130 0.3 A injectionComp. 8 PVDF 752 PEE MFR10 melted Comp. 9 Method 4 core: glass fiber yesPEE MFR10 melted sheath: PEE & cut Comp. 10 Method 4 core: carbon fiberyes PEE MFR10 melted sheath: PEE & cut*SF = stretched filament;Method 1 = SF-inserted injection→perforation→injection molding of spacerportion.Method 2 = tape extrusion→perforation→injection molding of spacerportionMethod 3 = tape extrusion→stretching→perforation→injection molding ofspacer portionMethod 4 = extrusion of core-containing tape→perforation→injectionmolding of spacer portionMethod 5 = extrusion of core-containingtape→stretching→perforation→injection molding of spacer portion**PEE = polyester elastomer, PVDF = polyvinylidene flouride, co-Ny =copolymer nylon.***molding defects (insufficient filling, fins) A = none, B = few, C =many

Example 14

As shown in FIG. 11, rollers were set at equal intervals in a mold, andthe stretched filament prepared in Example 1 was disposed at suchpositions as to be contained along two edges parallel to thelongitudinal direction of the resultant shaped product, and an identicalresin (polyester elastomer of MFR=1.0) as the stretched filament wasinjected into the mold to obtain a roller-type ball chain belt as shownin FIG. 12(a), (b) and (c) having a width of 2.24 mm, a thickness of0.24 mm, a hole in a width direction of 1.63 mm and a hole-hole pitch of1.73 mm. The stretched filament occupied a portion of sectional areaperpendicular to the longitudinal direction at ratios of 5% at aroller-retainer portion (spacer portion) and 43% at a hole diameterposition. The roller-type ball chain belt exhibited a high tensilestrength and also a high strength at the ball-retaining position, andfurther a good size stability due to a small thermal shrinkability. Thestretched filament exhibited a good adhesiveness without peeling.

Example 15

A ball chain was prepared by insetting balls in a ball chain beltobtained in the same manner as in Example 7. The ball chain was used toprepare a linear motion guide device as shown in FIG. 13 including atracking rail 12, a moving block body 13 and the ball chain 14.

Example 16

A roller-type ball chain was prepared by insetting rollers in a ballchain belt obtained in the same manner as in Example 14. The ball chainwas used to prepare a linear motion guide device 15 as shown in FIG. 14including a tracking rail 16, a moving block body 17 and the roller-typeball chain 18.

Example 17

A ball chain was prepared by insetting balls in a ball chain beltobtained in the same manner as in Example 7. The ball chain was used toprepare a ball screw 19 as shown in FIG. 15 including a screw shaft 20,a nut member 21, a return pipe 22 and the ball chain 23.

It became clear that the linear motion guide devices prepared inExamples 14 and 15 and the balk screw prepared in Example 17 allwithstood a long period of use, whereby it was proved that the ballchain belt and ball chain according to the present invention could beexcellent members of such linear motion guide device and ball screwdevice.

[Industrial Applicability]

According to the present invention of effecting injection molding aftersetting a stretched fibrous member in a mold, it is possible to obtain atape-shaped product having a large strength not attainable by aconventional extrusion product or a mere injection-molded product.

Further, a ball chain belt having a large strength obtained bysubjecting such a tape-shaped product to perforation and injectionmolding of portions for retaining rolling members (such as balls orrollers) or by injection molding after setting a stretched fibrousmember and balls for molding, is allowed to provide a product whichexhibits a large strength not realizable by a ball chain belt formed by(co-)extrusion. Further, the stretched fibrous member disposed alongboth edges of the shaped product not only contributes to the strengthbut also reinforces the weld and remarkably reduces the molding defects.

By insetting prescribed balls (or rollers) in the ball chain beltthus-obtained of the present invention, a ball chain is obtained. Theball chain can exhibit excellent performances when incorporated in alinear motion guide device equipped with an endless circulation path, ora ball screw, etc.

1. A tape-shaped product of synthetic resin, comprising: a tape of a thermoplastic resin, and a preliminarily stretched fibrous member of a thermoplastic resin contained therein along longitudinally parallel edges or in proximity thereto of the tape; wherein the thermoplastic resin forming the fibrous member is of a same family as the thermoplastic resin forming the tape.
 2. A tape-shaped product of synthetic resin according to claim 1, wherein the fibrous member is in a form of a monofilament.
 3. A tape-shaped product of synthetic resin according to claim 1, having a longitudinal tensile strength of at least 250 MPa and a thermal shrinkability of at most 1%.
 4. A belt for ball chain, comprising: a tape of synthetic resin, a preliminarily stretched fibrous member of thermoplastic resin contained therein along longitudinally parallel edges or in proximity thereto of the tape, and ball-insetting holes disposed at equal intervals in a straight line; wherein the thermoplastic resin forming the fibrous member is of a same family as the thermoplastic resin forming the tape.
 5. A belt for ball chain, comprising: a tape of synthetic resin, a preliminarily stretched fibrous member of thermoplastic resin contained therein along longitudinally parallel edges or in proximity thereto of the tape, ball-insetting holes disposed at equal intervals in a straight line, and projections disposed around the holes; wherein the thermoplastic resin forming the fibrous member is of a same family as the thermoplastic resin forming the tape.
 6. A belt for ball chain according to claim 4, wherein the fibrous member is in a form of a monofilament.
 7. A belt for ball chain according to claim 4, having a tensile strength of at least 100 MPa, and a thermal shrinkability of at most 1%.
 8. A method of producing a belt for ball chain, comprising: setting, in a mold, balls for molding each having a diameter slightly larger than balls to be retained in a resultant shaped product so as to be aligned in a straight line along a central portion of the resultant shaped product, and a preliminarily stretched fibrous member so as to be contained along longitudinally parallel edges or in proximity thereof of the resultant shaped product, injection-molding a moldable resin of a same family as the stretched fibrous member to form a tape portion and a retaining portion integrally, and then removing the balls for molding.
 9. A method of producing a belt for ball chain according to claim 8, wherein the fibrous member is in a form of a monofilament.
 10. A tape-shaped product of synthetic resin according to claim 2, having a longitudinal tensile strength of at least 250 MPa and a thermal shrinkability of at most 1%.
 11. A belt for ball chain according to claim 5, wherein the fibrous member is in a form of a monofilament.
 12. A belt for ball chain according to claim 5, having a tensile strength of at least 100 MPa, and a thermal shrinkability of at most 1%. 